Forked three-awned grass (Aristida basiramea) COSEWIC assessment and status report: chapter 11

Technical Summary

Aristida basiramea Engelm.

Forked Three-awned Grass – Aristide à rameaux basilaires

Range of Occurrence in Canada:

Ontario (ON) and Quebec (QC)

Extent and Area information

extent of occurrence (EO) (km²) :

30 sq km at Cazaville, 472 for the 4 Ontario stations total = 502

specify trend (decline, stable, increasing, unknown) :

unknown

are there extreme fluctuations in EO (> 1 order of magnitude)?

no

area of occupancy (AO) (km²) :

  • A total of <3 (ON and QC)
  • Quebec (Cazaville): 2 sq km
  • Ontario: <1 sq km
  • Macey: 12,000 sq m
  • Christian: 10,000 sq m
  • Beausoleil: 950 sq m
  • Anten Mills: 50 sq m

specify trend (decline, stable, increasing, unknown) :

Unknown

are there extreme fluctuations in AO (> 1 order magnitude)?

No

number of extant locations :

5

specify trend in # locations (decline, stable, increasing, unknown) :

Was stable since discovery of the 2 pops 20 and 25 years ago, and then doubled in 2001. One population soon to be heavily developed

are there extreme fluctuations in # locations (>1 order of magnitude)?

No

habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat :

Declining

Population information

Generation time (average age of parents in the population)(indicate years, months, days, etc.) :

Annual

Number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) :

  • >20,000 in total
  • (>10,000 in ON
  • >10,000 in QC)

total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals :

Unknown

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)

are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?

No

is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., < 1 successful migrant / year)?

Yes, its barren sand habitat is very localized and extremely fragmented in Ontario and Quebec, occurring as small remnants

list each population and the number of mature individuals in each :

Ontario

  • Macey Lake – 1000s
  • Christian Is. – >10,000
  • Beausoleil Is. – >500
  • Anten Mills – ca. 800

Quebec

  • Cazaville – >10,000

specify trend in number of populations (decline, stable, increasing, unknown) :

Increased search effort in 2001 and 2002 yielded 2 new sites in ON and 1 in QC

are there extreme fluctuations in number of populations (>1 order of magnitude)?

No

Threats (actual or imminent threats to populations or habitats)

  1. Limited habitat, restricted to sand barrens
  2. Sand extraction
  3. Successional changes
  4. Planting of conifers
  5. ATVs and trail bikes
  6. Subdivision development
  7. urban expansion/development

Rescue Effect (immigration from an outside source)

does species exist elsewhere (in Canada or outside)?

Exists in number of United States

status of the outside population(s)?

Rare in United States but unknown number where it is secure (no states have ranked it S4 or S5)

is immigration known or possible?

unlikely

would immigrants be adapted to survive here?

Yes

is there sufficient habitat for immigrants here?

Very little

Quantitative Analysis

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